Lubricating oil additive and lubricating oil composition

ABSTRACT

A lubricating oil additive and a lubricating oil composition wherein no precipitation is generated to exhibit a good storage stability even if a combination of a salicylate detergent and another metal detergent is used is provided by rendering the additive and composition an additive and a composition obtained by incorporating, into a lubricant base oil, (A) an alkali metal or alkaline earth metal salicylate having at its 3 and 5-positions hydrocarbon groups having 1 to 40 carbon atoms and a (per)basic salt, and (B) a metal detergent other than any salicylate detergent.

TECHNICAL FIELD

The present invention relates to a lubricating oil additive and alubricating oil composition, specifically, a lubricating oil additiveand a lubricating oil composition into which two or more metaldetergents are incorporated to exhibit good storage stability.

BACKGROUND ART

Lubricating oils are required to have various performances in accordancewith their use purposes. In particular, engine oils are required to havehigh thermal stability, high-temperature detergency, oxidizationstability, wear prevention and others, and are produced by incorporatinglubricating oil additives such as an anti-wear agent, an ashlessdispersing agent, a metal detergent, and an antioxidant thereinto.Examples of the metal detergent include such as salicylates, phenatesand sulfonates. These are used alone or in combination in order toimprove the high-temperature detergency and other properties oflubricating oils.

About such a technical field, for example, patent document 1 (JapanesePatent Application Laid-Open (JP-A) No. 8-176583) and patent document 2(JP-A No. 10-53784) disclose diesel engine oil compositions into which acombination of metal detergents having different base numbers isincorporated.

However, the following have been coming to light: in the case of using acombination of a monoalkyl salicylate and a metal detergent (such as asulfonate) other than any salicylate both of which have been in generalcommercially available and used hitherto, calcium carbonate and others,which are dispersed in the metal detergent, precipitate when thecomposition is stored, so as to cause the following problems: theclogging of a producing line filter, a shipping line filter, an enginefilter and so on for the lubricating oil additives and the lubricatingoil; a drop in qualities required as products of the lubricating oiladditives or the lubricating oil, such as a drop in the base numberthereof; the generation of abnormal abrasion when the composition isactually used; and others. In particular, in the case of using amonoalkyl salicylate made into a (per)base by use of calcium carbonate,calcium borate or the like together with a neutral or (per)basicsulfonate detergent, in particular, a neutral sulfonate, precipitationis generated at an early stage. Thus, this combination cannot bevirtually used in any lubricating oil additive or lubricating oilproduct under the present circumstances. Thus, the circumstances havebeen desired to be improved.

DISCLOSURE OF THE INVENTION

In light of situations as described above, it is an object of thepresent invention to provide a lubricating oil additive and alubricating oil composition which comprise a combination of a salicylatedetergent and a metal detergent other than it wherein no precipitationis generated to exhibit a good storage stability. Patent document 2,paragraph (0010) specifically describes SAP 001, SAP 005, and SAP 007manufactured by Shell Chemicals Japan and OSCA 435B and OSCA 463manufactured by Osca Chemical as examples of a “highly basic calciumsalicylate/magnesium salicylate”, and patent document 2, paragraph(0012) specifically describes SAP 002 manufactured by Shell ChemicalsJapan and OSCA 431B manufactured by Osca Chemical as “low basic calciumsalicylates”. However, all of these commercially available products areproducts made mainly of a monoalkyl type salicylate (the constituentratio of the monoalkyl salicylate in the salicylate structure thereof isover 90% by mole). Furthermore, patent documents 1 and 2 are not evenaware of problems as described above.

The inventors have paid attention to the structure of a salicylate as ametal detergent, and made eager investigations to find out that in thecase of using a combination of a salicylate having a specific structureand a metal detergent other than any salicylate, no precipitation isgenerated in the form of a lubricating oil additive or a lubricating oilcomposition so that a very good storage stability is exhibited. Thus,the present invention has been made.

Accordingly, the present invention is a lubricating oil additive and alubricating oil composition obtained by incorporating, into a lubricantbase oil, (A) a salicylate detergent and (B) a metal detergent otherthan any salicylate detergent, wherein the salicylate detergent (A) isan alkali metal or alkaline earth metal salicylate represented by thegeneral formula (1) and/or a (per)basic salt thereof:

wherein R¹ and R² may be the same or different and each represent ahydrocarbon group having 1 to 40 carbon atoms, the hydrocarbon group maycontain oxygen or nitrogen, M represents an alkali metal or alkalineearth metal, and n is 1 or 2 in accordance with the valence of themetal.

It is preferred that one of R¹ and R² in the general formula (1) is ahydrocarbon which has 10 to 40 carbon atoms, and the other is ahydrocarbon which has less than 10 carbon atoms (and may have oxygen ornitrogen) or R¹ and R² are each a hydrocarbon group having 10 to 40carbon atoms.

The lubricating oil additive and the lubricating oil composition of thepresent invention are particularly useful in the case where the metalratio of the component (A) is 1.1 or more.

It is preferred that the metal detergent (B) other than any salicylatedetergent is at least one selected from alkali metal or alkaline earthmetal sulfonates, alkali metal or alkaline earth metal phenates, and(per)basic salts thereof.

It is preferred that the lubricating oil additive and the lubricatingoil composition of the present invention further comprise at least onelubricating oil additive selected from (C) an anti-wear agent, (D) anashless dispersing agent, and (E) an antioxidant.

BEST MODES FOR CARRYING OUT THE INVENTION

The present invention will be described in detail hereinafter.

As the lubricant base oil in the lubricating oil additive and thelubricating oil composition of the present invention, a mineral typebase oil or synthetic type base oil that is used in ordinary lubricatingoil can be used without any especial limit.

Specific examples of the mineral oil type base oil include oils obtainedby purifying a lubricating oil fraction yielded by distilling anatmospheric residue oil, which is obtained by distilling crude oil undernormal pressure, under reduced pressure by at least one selected fromsolvent deasphalting, solvent extraction, hydrocracking, solventdewaxing, hydrorefining and other treatments; wax-isomerized mineraloils; and base oils produced by isomerizing GTL wax (gas-to-liquid wax).

Specific examples of the synthetic type base oil include polybutene orhydrogenated products thereof; poly-α-olefins, such as 1-octene oligomerand 1-decene oligomer, or hydrogenated products thereof; diesters suchas ditridecyl glutarate, di-2-ethylhexyl adipate, diisodecyl adipate,ditridecyl adipate and di-2-ethylhexyl cebacate; polyol esters such astrimethylolpropane caprilate, trimethylolpropane pelargonate,pentaerythritol-2-ethyl hexanoate, and pentaerythritol pelargonate; andaromatic synthesis oils such as alkylnaphthalene, alkylbenzene, andaromatic esters; and mixtures thereof.

In the invention, the above-mentioned mineral oil type base oils, theabove-mentioned synthetic type base oils, or any mixture composed of twoor more lubricating oils selected therefrom can be used. Examplesthereof include one or more out of the mineral oil type base oils, oneor more out of the synthetic type base oils, and a mixture of one ormore out of the mineral oil type base oils and one or more out of thesynthetic type base oils.

The aromatic fraction content in the lubricant base oil is notparticularly limited, and the content as % CA is preferably 10 or less,more preferably 3 or less, in particular preferably 2 or less by mass.When the aromatic fraction content in the base oil is set as describedabove, a composition better in oxidation stability can be obtained. The“% C_(A)” represents the percentage of the number of the aromatic carbonatoms to the number of all the carbon atoms, the percentage beingobtained by ring analysis prescribed in ASTM D 3238.

The kinematic viscosity of the lubricant base oil is not particularlylimited, and the kinematic viscosity at 100° C. is preferably 20 mm²/sor less, more preferably 10 mm²/S or less in order to keep thelow-temperature viscosity property good. On the other hand, thekinematic viscosity is preferably 1 mm²/s or more, more preferably 2mm²/S or more in order to form a sufficient oil film at lubricationplaces, thereby keeping lubricity and further control the evaporationloss of the lubricant base oil into a low value.

The evaporation loss quantity of the lubricant base oil is 20% or lessby mass, more preferably 16% or less by mass, and in particularpreferably 10% or less by mass as NOACK evaporation quantity. When theNOACK evaporation quantity of the lubricant base oil is kept at a valueof 20% or less by mass, the evaporation loss of the lubricating oil canbe controlled into a low value and further in the case of using thelubricating oil composition as a lubricating oil for internal combustionengine, it is possible to prevent sulfur compounds, phosphorus compoundsor metals in the composition from being deposited together with thelubricant base oil on an exhaust gas purifying device so as to prevent abad effect on the exhaust gas purifying performance in advance. TheNOACK evaporation quantity referred to herein is measured in accordancewith CEC L-40-T-87.

The viscosity index of the lubricant base oil is not particularlylimited, and the value thereof is preferably 80 or more, more preferably100 or more, and even more preferably 120 or more to obtain a goodviscometric property at temperatures from low temperature and hightemperature.

The component (A) in the invention is an alkali metal or alkaline earthmetal salicylate represented by the general formula (1) and/or a(per)basic salt thereof:

wherein R¹ and R² may be the same or different and each represent ahydrocarbon group having 1 to 40 carbon atoms, the hydrocarbon group maycontain oxygen or nitrogen, M represents an alkali metal or alkalineearth metal such as sodium, potassium, calcium and magnesium, and ispreferably calcium or magnesium, more desirably calcium, and n is 1 or 2in accordance with the valence of the metal.

Examples of the hydrocarbon group having 1 to 40 carbon atoms includealkyl, cycloalkyl, alkenyl, alkyl-substituted cycloalkyl, aryl,alkyl-substituted aryl and arylalkyl groups. Specific examples thereofinclude alkyl groups which have 1 to 40 carbon atoms (and may be linearor branched) such as methyl, ethyl, propyl, butyl, pentyl, hexyl,heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl,heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, hexacosyl,heptacosyl, octacosyl, nonacosyl, and triacontyl groups; cycloalkylgroups having 5 to 7 carbon atoms such as cyclopentyl, cyclohexyl andcycloheptyl; alkylcycloalkyl groups having 6 to 10 carbon atoms (theposition(s) where the alkyl group(s) is/are substituted on thecycloalkyl group being arbitrary) such as methylcyclopentyl,dimethylcyclopentyl, methylethylcyclopentyl, diethylcyclopentyl,methylcyclohexyl, dimethylcyclohexyl, methylethylcyclohexyl,diethylcyclohexyl, methylcycloheptyl, and dimethylcycloheptyl,methylethylcycloheptyl; alkenyl groups (which may be linear or branched,the position of the double bond therein being arbitrary) such asbutenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl,undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl,hexadecenyl, heptadecenyl, octadecenyl and nonadecenyl groups; arylgroups such as phenyl and naphthyl groups; alkylaryl groups having 7 to10 carbon atoms (wherein the alkyl group(s) may be linear or branched,the position(s) where the alkyl group(s) is/are substituted on the arylgroup being arbitrary) such as tolyl, xylyl, ethylphenyl, propylphenyl,and butylphenyl groups; and arylalkyl groups which have 7 to 10 carbonatoms (the alkyl group being allowable to be linear or branched) such asbenzyl, phenylethyl, phenylpropyl, and phenylbutyl groups.

R¹ can be combined with R² without any especial limitation. Preferredexamples of the combination thereof are the following combination (1) or(2):

-   (1) One of R¹ and R² is a hydrocarbon group having 10 to 40 carbon    atoms, preferably 10 to less than 20 carbon atoms, or 20 to 30    carbon atoms, and the other is a hydrocarbon having less than 10    carbon atoms, preferably less than 5 carbon atoms, in particular    preferably 1 carbon atom; or-   (2) R¹ and R² are each a hydrocarbon group having 10 to 40 carbon    atoms, preferably 10 to less than 20 carbon atoms, or 20 to 30    carbon atoms, and these are preferably the same as each other.

The hydrocarbon group having 10 to 40 carbon atoms is preferably asecondary alkyl group derived from a polymer or copolymer made fromethylene, propylene, butylene or the like and represented by thefollowing general formula (2):

wherein x and y are each an integer from 0 to 37 and x+y is from 7 to37; preferably, x and y are each an integer from 0 to 27 and x+y is from7 to 27; more preferably, x and y are each an integer from 0 to 16 andx+y is from 7 to 16 or x and y are each an integer from 0 to 23 and x+yis from 17 to 23; and in particular preferably, x and y are each aninteger from 0 to 15 and x+y is from 11 to 15.

The hydrocarbon having less than 10 carbon atoms may be an alkyl grouphaving 1 to less than 10 carbon atoms such as a methyl, ethyl, butyl, ort-butyl group, and may contain oxygen or nitrogen. An example thereof isa —COOH group. Of these, t-butyl and methyl groups are preferable and amethyl group is most preferable.

The process for producing the component (A) is not particularly limited,and a known process disclosed in JP-B-48-35325, JP-B-50-3082 or the likecan be used. For example, in the case where one of R¹ and R² is an alkylgroup having 10 to less than 20 carbon atoms or 20 to 30 carbon atomsand the other is a methyl group, the component (A) can be obtained byusing an o-cresol or p-cresol as a starting material to alkylate thep-position or o-position thereof with an olefin having 10 to less than20 carbon atoms or 20 to 30 carbon atoms, carboxylating the resultant,and further causing the resultant to react with a metal base such as anoxide or hydroxide of an alkali metal or alkaline earth metal orconverting the resultant once into an alkali metal salt such as a sodiumor potassium salt and then substituting the salt with an alkaline earthmetal salt. In the case where phenol is used as a starting material, itis advisable to produce the component (A) through steps of using anolefin having 10 to less than 20 carbon atoms or 20 to 30 carbon atomsin an amount of 1.5 to 4 moles, preferably 2 to 3 moles per mole ofphenol to conduct alkylation followed by carboxylation (or steps reversethereto).

About the component (A) in the invention, salicylates other than thesalicylate represented by the general formula (1), that is, monoalkylsalicylates having 1 to 40 carbon atoms such as 3-alkyl salicylate,4-alkyl salicylate and 5-alkyl salicylate may be contained as componentsresulting from impurities in the process of producing the salicylaterepresented by the general formula (1) or as optional components. Theconstituent ratio thereof is preferably 50% or less by mole, morepreferably 30% or less by mole, even more preferably 10% or less bymole, most preferably approximately 0% by mole. In the case where thecontent of the monoalkyl salicylate(s) is restricted as described above,a composition wherein the generation of a precipitation is suppressedcan be obtained when the component (A) is used together with a sulfonateor the like. In the case of, for example, 3-alkyl-5-methyl salicylate,3-methyl-5-alkyl salicylate or the like, which is obtained by use ofo-cresol or p-cresol as a starting material as described above,monoalkyl salicylates are not substantially contained. In the case of adialkyl salicylate, which is obtained by use of the above-mentionedphenol as a starting material, the content of monoalkyl salicylate(s)can be decreased by using an olefin in an amount of 2 moles or more perthe phenol to conduct alkylation or by separating and removing monoalkylsalicylate(s) from the resultant mono- and di-alkyl salicylate mixture.

The component (B) in the lubricating oil additive and the lubricatingoil composition of the invention is a metal detergent other than anysalicylate detergent. That is, examples thereof include alkali metal oralkaline earth metal detergents made of sulfonates, phenates,carboxylates and naphthenates of alkali metal or alkaline earth metals.In the invention, one or more alkali metal or alkaline earth metaldetergents can be used which are selected from the group consisting ofthe above. Alkaline earth metal sulfonate detergents and alkaline earthmetal phenate detergents, in particular, alkaline earth metal sulfonatedetergents are preferably used.

The alkaline earth metals are each an alkaline earth metal salt, inparticular, a magnesium salt and/or a calcium salt of an alkyl aromaticsulfonic acid obtained by sulfonating an alkyl aromatic compound havinga molecular weight of 300 to 1500, preferably 400 to 700, and thecalcium salt is preferably used.

Specific examples of the alkyl aromatic sulfonic acid include petroleumsulfonic acid and synthetic sulfonic acid.

As the petroleum sulfonic acid, there is generally used a sulfonatedalkyl aromatic compound of a lubricant fraction of mineral oil or theso-called mahogany acid, which is produced as a byproduct when white oilis produced. As the synthetic sulfonic acid, there is used, for example,a sulfonated alkylbenzene having a linear or branched alkyl group, whichis obtained by alkylating benzene with an oligomer of an olefin having 2to 12 carbon atoms (such as ethylene or propylene), or a productobtained by sulfonating an alkylnaphthalene such as dinonylnaphthalene.The sulfonating agent used when these alkyl aromatic compounds aresulfonated is not limited to any especial kind. Usually, fuming sulfuricacid or sulfuric anhydride is used.

Examples of the alkaline earth metal phenates include alkaline earthmetal salts, in particular, magnesium and calcium salts of Mannichreactants of alkyl phenol, alkylphenol sulfide or alkylphenol. Specificexamples thereof include substances represented by the followingformulae (3), (4) and (5):

wherein R²¹, R²², R²³, R²⁴, R²⁵ and R²⁶ may be the same or different andeach represent a linear or branched alkyl group having 4 to 30 carbonatoms, preferably 6 to 18 carbon atoms, and M¹, M² and M³ each representan alkaline earth metal, preferably calcium or magnesium, and xrepresents 1 or 2.

Specific examples of R²¹, R²², R²³, R²⁴, R²⁵ and R²⁶, which are eachindependent, include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl,undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl,heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl,tricosyl, tetracosyl, pentacosyl, hexacosyl, heptacosyl, octacosyl,nonacosyl, and triacontyl groups. These may be linear or branched. Thesemay also be primaryl alkyl, secondary alkyl or tertiary alkyl groups.

Examples of the component (A) and component (B) of the invention includenot only neutral salts as described above but also basic salts obtainedby heating these neutral salts together with an excessive amount of analkali metal or alkaline earth metal salt or an alkali metal or alkalineearth metal base (a hydroxide or oxide of an alkali metal or alkalineearth metal) in the presence of water; and perbasic salts obtained bycausing the neutral salts to react with a base such as a hydroxide of analkali metal or alkaline earth metal in the presence of carbon dioxidegas, boric acid or a borate.

These reactions are usually conducted in a solvent (an aliphatichydrocarbon solvent such as hexane, an aromatic hydrocarbon solvent suchas xylene, a light lubricant base oil, or the like), so as to yieldsalts having a metal content of 1.0 to 20% by mass, preferably 2.0 to16% by mass.

In the invention, the metal ratio of the component (A) or component (B)is not particularly limited, and the component (A) and component (B)having a metal ratio of 1 to 40, preferably 1 to 20 can be used. Themetal ratio of the component (A) is 1.1 or more, preferably 1.5 or more,in particular preferably 2.3 or more, and is preferably 10 or less, morepreferably 6 or less since the salicylate which may generate aprecipitation is a monoalkyl salicylate made into a (per)base withcalcium carbonate or the like. The component (A) having a metal ratiowithin such a range is very useful. In the case of using theabove-mentioned monoalkyl salicylate, which has a metal ratio of 1.1 ormore, for example, a monoalkyl salicylate having a metal ratio of 2.7together with a sulfonate detergent as the component (B), aprecipitation is generated whether the metal ratio of the sulfonatedetergent is 1 or 10. However, as the metal ratio of the sulfonatedetergent is smaller (in the case where the ratio is, for example, 5 orless, or 2 or less, in particular 1), a precipitation is generated at anearlier stage. It is therefore very useful to use the component (B)having such a small metal ratio together with the component (A) having ametal ratio as described above. In the case where the metal ratios ofthe components (A) and (B) are each 1, a precipitation resulting fromcalcium carbonates or the like is not generated. Thus, this case is alsopreferred.

The metal ratio referred to herein is represented by (the valence of themetal element in an alkali metal or alkaline earth metal salicylate, analkali metal or alkaline earth metal sulfonate, or the like)×(content (%by mole) of the metal element therein/(content (% by mole) of the soapgroup therein). The metal element means calcium, magnesium or the like,and the soap group means the alkylsalicylic acid group, thealkylsulfonic acid group, or the like.

In the lubricating oil additive and the lubricating oil composition ofthe invention, the contents of the component (A) and the component (B)are not particularly limited, and are decided as the needs arise for alubricating oil additive or a lubricating oil product. The lower limitof each of the contents is 0.01% by mass, preferably 0.1% by mass of thewhole of the composition. The upper limit thereof is 40% by mass,preferably 20% by mass, in particular preferably 10% or less by mass.When the composition of the invention is used as a lubricating oilcomposition for internal combustion engine, preferred examples of thecontents of the component (A) and the component (B) are as follows: theamount of the component (A) is 5% or less by mass, preferably 1% or lessby mass, more preferably 0.5% or less by mass, even more preferably 0.3%or less by mass of the whole of the lubricating oil composition, and theamount of the component (B) is 5% or less by mass, preferably 1% or lessby mass, more preferably 0.5% or less by mass, even more preferably 0.3%or less by mass, most preferably 0.15% or less by mass of the whole ofthe lubricating oil composition, these amounts being in terms of theamounts of the alkali metal or alkaline earth metal element. In the caseof the component (B) (in particular, a sulfonate) having a metal ratioof 2 or less, it is desired that the component is incorporatedpreferably in an amount of 0.08% or less by mass, in particularpreferably in an amount of 0.05% or less by mass since the content ofthe soap group (such as sulfonic acid) becomes relatively high.

The lubricating oil additive and the lubricating oil composition of theinvention are a lubricating oil additive and a lubricating oilcomposition wherein the component (A) and the component (B) areincorporated into a lubricant base oil, and are good in not only storagestability but also high-temperature detergency, base numbermaintainability, oxidization stability and others. In order to make theperformances better and make other required performances better, one ormore additives may be arbitrarily incorporated thereinto, the additivesbeing selected from (C) an anti-wear agent, (D) an ashless dispersingagent, and (E) an antioxidant, or from known additives such as afriction modifier, a viscosity index improver, a corrosion inhibitor, arust inhibitor, an anti-emulsifier, a metal inactivator, an antifoamingagent, and a colorant. The resultant composition can be supplied as anadditive package or lubricating oil product into which these areincorporated.

Examples of the anti-wear agent (C) include sulfur-containing compoundssuch as zinc dithiophosphate, zinc dithiocarbamate, thiophosphoric acidesters, disulfides, olefin sulfides, and oil and fat sulfides;monoesters or diesters of phosphorous acid or phosphoric acid, metal(such as zinc) salts thereof, and amine salts thereof; and triesters ofphosphorous acid or phosphoric acid. These may be incorporated usuallyat a ratio of 0.1 to 20% by mass, preferably at a ratio of 0.2 to 10% bymass. The component (A) in the invention less easily hinders the effectof the anti-wear agent (C) than any monoalkyl type salicylate;therefore, when the component (C) is used in the lubricating oilcomposition of the invention, the content thereof can be decreased. Inthe case of, for example, an anti-wear agent containing sulfur, theamount of the agent (C) can be 0.2% or less by mass, preferably 0.15% orless by mass of the whole of the lubricating oil composition, the amountbeing in terms of the amount of the sulfur element therein. In the caseof, for example, an anti-wear agent containing phosphorus, the amount ofthe agent (C) can be 0.08% or less by mass, more restrictedly 0.05% orless by mass of the whole of the lubricating oil composition, the amountbeing in terms of the amount of the phosphorus element therein. Such acase is useful when the composition of the invention is used as alubricating oil composition for internal combustion engine. This isbecause a bad effect thereof onto an exhaust gas purifying catalyst canbe decreased.

Examples of the ashless dispersing agent (D) include succinimide ashlessdispersing agents, benzylamine ashless dispersing agents,polybutenylamine ashless dispersing agents, and compounds obtained bymodifying these compounds with a boron compound, a oxygen-containingorganic compound, a phosphorus compound, a sulfur compound or the like.These may be incorporated usually at a ratio of 0.1 to 20% by mass,preferably at a ratio of 0.5 to 10% by mass.

As the antioxidant (E), any antioxidant that is ordinarily used inlubricating oil can be used, examples thereof including phenol typeantioxidants such as 2,6-di-tert-butyl-4-methylphenol,4,4′-methylenebis(2,6-di-tert-butylphenol),octyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, andoctyl-3-(3-methyl-5-tert-butyl-4-hydroxyphenyl)propionate, amine typeantioxidants such as phenyl-α-naphthylamine,alkylphenyl-α-naphthylamine, and dialkyldiphenylamine, and metal typeantioxidants such as molybdenum and copper antioxidants. These may beincorporated usually at a ratio of 0.1 to 10% by mass, preferably at aratio of 0.1 to 5% by mass.

Examples of the friction modifier include molybdenum dithiophosphate,molybdenum dithiocarbamate, aliphatic acid esters, aliphatic amines,aliphatic amides, and aliphatic ethers.

Specific examples of the viscosity index improver include the so-callednon-dispersion type viscosity index improvers, which are polymers orcopolymers made from one or more monomers selected from variousmethacrylic acid esters, or hydrogenated products thereof; the so-calleddispersion type viscosity index improvers, which are obtained bycopolymerizing them further with various methacrylic acid esterscontaining a nitrogen compound; non-dispersion type or dispersion typeethylene/α-olefin copolymers (examples of the α-olefin includingpropylene, 1-butene and 1-pentene), or hydrogenated products thereof;polyisobutylene, or hydrogenated products thereof; hydrogenated productsof styrene/diene copolymer; styrene/anhydrous maleic acid estercopolymer; and polyalkylstyrene.

It is necessary that the molecular weight of these viscosity indeximprovers is selected, considering shear stability. Specifically, thenumber-average molecular weight of the viscosity index improvers isusually from 5,000 to 1,000,000, preferably from 100,000 to 900,000 inthe case of, for example, the dispersion type and the non-dispersiontype polymethacrylates; is usually from 800 to 5,000, preferably from1,000 to 4,000 in the case of the polyisobutylene or the hydrogenatedproducts thereof; and is usually from 800 to 500,000, preferably from3,000 to 200,000 in the case of the ethylene/α-olefin copolymers or thehydrogenated products thereof.

In the case where the ethylene/α-olefin copolymers or the hydrogenatedproducts thereof are used out of these viscosity index improvers, alubricating oil additive and a lubricating oil composition particularlygood in shear stability can be obtained. One or more compounds selectedat will from the above-mentioned viscosity index improvers can becontained in an arbitrary amount.

Examples of the corrosion inhibitor include benztriazole type,tolyltriazole type, thiadiazole type, and imidazole type compounds.

Examples of the rust inhibitor include petroleum sulfonate,alkylbenzenesulfonate, dinonylnaphthalenesulfonate, alkenylsuccinic acidesters, and polyhydric alcohol esters.

Examples of the anti-emulsifier include polyalkylene glycol typenonionic surfactants such as polyoxyethylene alkyl ether,polyoxyethylene alkyl phenyl ether and polyoxyethylene alkyl naphthylether.

Examples of the metal inactivator include imidazolin, pyrimidinederivatives, alkylthiadiazole, mercaptobenzothiazole, benzotriazole orderivatives thereof, 1,3,4-thiadiazole polysulfide,1,3,4-thiazolyl-2,5-bisdialkyldithiocarbamate,2-(alkyldithio)benzimidazole, and β-(o-carboxybenzylthio)propionitrile.

Examples of the antifoamer include silicone, fluorosilicone, andfluoroalkyl ether.

In the case where these additives are incorporated into the lubricatingoil additive of the invention, these additives can be appropriatelyadded in accordance with the use purpose of a lubricating oilcomposition wherein the lubricating oil additive is to be used, so as toconstruct the so-called additive package. When one of these additives isincorporated into the lubricating oil composition of the invention, thecontent thereof is usually selected from the range of 0.1 to 5% by massof the whole of the lubricating oil composition in the case of thefriction modifier, from the range of 0.1 to 20% by mass thereof in thecase of the viscosity index improver, from the range of 0.005 to 5% bymass thereof in the case of the corrosion inhibitor, the rust inhibitoror the anti-emulsifier, form the range of 0.005 to 1% by mass thereof inthe case of the metal inactivator, and from the range of 0.0005 to 1% bymass thereof in the case of the antifoamer.

EXAMPLES

The content of the present invention will be more specifically describedby way of the following examples and comparative examples. However, theinvention is not limited by these examples.

Examples 1 to 8, and Comparative Examples 1 to 8

As shown in Tables 1 and 2, lubricating oil compositions of theinvention (Examples 1 to 8) and lubricating oil compositions forcomparison (Comparative Examples 1 to 8) were each prepared. TABLE 1Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7Example 8 Hydro-refined mineral oil 1) % by mass Balance Balance BalanceBalance Solvent refined mineral oil 2) % by mass Balance Balance BalanceBalance Perbasic Ca monoalkylsalicylate 1 3) % by mass — — — — — — — —Amount in terms of the alkaline earth % by mass — — — — — — — — metalelement Perbasic Ca monoalkylsalicylate 2 4) % by mass — — — — — — — —Amount in terms of the alkaline earth % by mass — — — — — — — — metalelement (A) Perbasic Ca 3-alkyl-5-methylsalicylate % by mass 4 4   2.5  2.5 — — — — 5) Amount in terms of the alkaline earth % by mass (0.24)(0.24) (0.18) (0.18) — — — — metal element (A) Perbasic Cadialkylsalicylate 6) % by mass — — — — 4 4   2.5   2.5 Amount in termsof the alkaline earth % by mass — — — — (0.24) (0.24) (0.18) (0.18)metal element (B) Neutral Ca sulfonate 7) % by mass 1 1 — — 1 1 — —Amount in terms of the alkaline earth % by mass (0.02) (0.02) — — (0.02)(0.02) — — metal element (B) Perbasic ca sulfonate 8) % by mass — — 1 1— — 1 1 Amount in terms of the alkaline earth % by mass — — (0.1) (0.1)  — — (0.1)  (0.1)  metal element (C)ZDTP 9) % by mass 1 1 1 1 1 11 1 Amount in terms of the phosphorus % by mass (0.07) (0.07) (0.07)(0.07) (0.07) (0.07) (0.07) (0.07) element (D) Ashless dispersing agent10) % by mass 5 5 5 5 5 5 5 5 (E) Antioxidant 11) % by mass 2 2 2 2 2 22 2 Viscosity index improver 12) % by mass 4 4 4 4 4 4 4 4Anti-emulsifier 13) % by mass   0.01   0.01   0.01   0.01   0.01   0.01  0.01   0.01 Storage stability test (vol %) 1 WEEK Not Not Not Not NotNot Not Not generated generated generated generated generated generatedgenerated generated 2 WEEK Not Not Not Not Not Not Not Not generatedgenerated generated generated generated generated generated generated 3WEEK Not Not Not Not Not Not Not Not generated generated generatedgenerated generated generated generated generated 4 WEEK Not Not Not NotNot Not Not Not generated generated generated generated generatedgenerated generated generated1) % C_(A): 0, Sulfur content: 0 ppm by mass, 100° C. kinematicviscosity: 6.5 mm²/s, viscosity index: 1252) % C_(A): 6.5, Sulfur content: 1700 ppm by mass, 100° C. kinematicviscosity: 6.9 mm²/s, viscosity index: 1003) Infineum C9371(SAP001) Total base value: 170 mgKOH/g, Ca content:6.1% by mass, Metal ratio: 2.7, Alkyl groups: C14, C16, C18, Constituentratio of monoalkyl compounds: 96 mol %4) OSCA463 Total base value: 170 mgKOH/g, Ca content: 6.1% by mass,Metal ratio: 2.7, Alkyl groups: C14, C16, C18, Constituent ratio ofmonoalkyl compounds: 95 mol %5) Total base value: 170 mgKOH/g, Ca content: 6.1% by mass, Metal ratio:2.7, Alkyl groups: C14, C16, C186) Total base value: 170 mgKOH/g, Ca content: 6.1% by mass, Metal ratio:2.7, Alkyl groups: C14, C16, C187) Total base value: 20 mgKOH/g, Ca content: 2.35% by mass, Metal ratio:1.08) Total base value: 300 mgKOH/g, Ca content: 10.4% by mass, Metalratio: 10.09) Alkyl group: 1,3-dimethylbutyl group, Phosphorus content: 7.2% bymass, Sulfur content: 14.4% by mass10) Polybutenylsuccnimide, Number-average molecular weight of thepolybutenyl groups: 130011) Phenol type and amine type antioxidants (1:1)12) OCP Average molecular weight: 15000013) Anti-emulsifier: polyoxyethylene alkyl ether

TABLE 2 Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar-ative ative ative ative ative ative ative ative example 1 example 2example 3 example 4 example 5 example 6 example 7 example 8Hydro-refined mineral oil 1) % by mass Balance Balance Balance BalanceSolvent refined mineral oil 2) % by mass Balance Balance Balance BalancePerbasic Ca monoalkylsalicylate 1 3) % by mass 4 4   2.5   2.5 — — — —Amount in terms of the alkaline earth % by mass (0.24) (0.24) (0.18)(0.18) — — — — metal element Perbasic Ca monoalkylsalicylate 2 4) % bymass — — — — 4 4   2.5   2.5 Amount in terms of the alkaline earth % bymass — — — — (0.24) (0.24) (0.18) (0.18) metal element (A) Perbasic Ca3-alkyl-5-methylsalicylate % by mass — — — — — — — — 5) Amount in termsof the alkaline earth % by mass — — — — — — — — metal element (A)Perbasic Ca dialkylsalicylate 6) % by mass — — — — — — — — Amount interms of the alkaline earth % by mass — — — — — — — — metal element (B)Neutral Ca sulfonate 7) % by mass 1 1 — — 1 1 — — Amount in terms of thealkaline earth % by mass (0.02) (0.02) — — (0.02) (0.02) — — metalelement (B) Perbasic ca sulfonate 8) % by mass — — 1 1 — — 1 1 Amount interms of the alkaline earth % by mass — — (0.1)  (0.1)  — — (0.1) (0.1)  metal element (C)ZDTP 9) % by mass 1 1 1 1 1 1 1 1 Amount interms of the phosphorus % by mass (0.07) (0.07) (0.07) (0.07) (0.07)(0.07) (0.07) (0.07) element (D) Ashless dispersing agent 10) % by mass5 5 5 5 5 5 5 5 (E) Antioxidant 11) % by mass 2 2 2 2 2 2 2 2 Viscosityindex improver 12) % by mass 4 4 4 4 4 4 4 4 Anti-emulsifier 13) % bymass   0.01   0.01   0.01   0.01   0.01   0.01   0.01   0.01 Storagestability test (vol %) 1 WEEK Generated Generated Not Not GeneratedGenerated Not Not (0.3) (0.3) Generated Generated (0.3) (0.3) GeneratedGenerated 2 WEEK Generated Generated Generated Generated GeneratedGenerated Generated Generated (0.3) (0.3) (0.02) (0.02) (0.3) (0.3)(0.02) (0.02) 3 WEEK Generated Generated Generated Generated GeneratedGenerated Generated Generated (0.3) (0.3) (0.02) (0.02) (0.3) (0.3)(0.02) (0.02) 4 WEEK Generated Generated Generated Generated GeneratedGenerated Generated Generated (0.3) (0.3) (0.02) (0.02) (0.3) (0.3)(0.02) (0.02)1) % C_(A): 0, Sulfur content: 0 ppm by mass, 100° C. kinematicviscosity: 6.5 mm²/s, viscosity index: 1252) % C_(A): 6.5, Sulfur content: 1700 ppm by mass, 100° C. kinematicviscosity: 6.9 mm²/s, viscosity index: 1003) Infineum C9371(SAP001) Total base value: 170 mgKOH/g, Ca content:6.1% by mass, Metal ratio: 2.7, Alkyl groups: C14, C16, C18, Constituentratio of monoalkyl compounds: 96 mol %4) OSCA463 Total base value: 170 mgKOH/g, Ca content: 6.1% by mass,Metal ratio: 2.7, Alkyl groups: C14, C16, C18, Constituent ratio ofmonoalkyl compounds: 95 mol %5) Total base value: 170 mgKOH/g, Ca content: 6.1% by mass, Metal ratio:2.7, Alkyl groups: C14, C16, C186) Total base value: 170 mgKOH/g, Ca content: 6.1% by mass, Metal ratio:2.7, Alkyl groups: C14, C16, C187) Total base value: 20 mgKOH/g, Ca content: 2.35% by mass, Metal ratio:1.08) Total base value: 300 mgKOH/g, Ca content: 10.4% by mass, Metalratio: 10.09) Alkyl group: 1,3-dimethylbutyl group, Phosphorus content: 7.2% bymass, Sulfur content: 14.4% by mass10) Polybutenylsuccnimide, Number-average molecular weight of thepolybutenyl groups: 130011) Phenol type and amine type antioxidants (1:1)12) OCP Average molecular weight: 15000013) Anti-emulsifier: polyoxyethylene alkyl ether

About the resultants compositions, the following storage stability testwas made.

(1) Storage Stability Test

A volume of 100 mL of each of the resultants lubricating oilcompositions was put into a graduated test tube for centrifugation (see,for example, JIS K 2601), and the following cycle test was made: 0° C.for one week→60° C. for 1 week→0° C. for 1 week→60° C. for 1 week. Itwas checked with the naked eye whether or not a precipitation wasgenerated.

Examples 1 to 8

Lubricating oil compositions of Examples 1 to 8 according to theinvention were each a composition obtained by incorporating, into alubricant base oil, calcium-carbonate-perbasic calcium(3-alkyl-5-methyl)salicylate or calcium (3,5-dialkyl)salicylate having ametal ratio of 2.7 as a component (A), calcium-carbonate-perbasiccalcium sulfonate having a metal ratio of 1 or 10 as a component (B),(C) zinc dithiophosphate, (D) succinimide, (E) phenol type and aminetype antioxidants, a viscosity index improver, and an anti-emulsifier.No precipitation was generated even after 4 weeks passed in theabove-mentioned cycle test, so as to exhibit good storage stability.Calcium phenate having a metal ratio of 1 was used as the component (B).As a result, no precipitation was generated in the same manner, so as toexhibit good storage stability.

Comparative Examples 1 to 8

In the case of using, as the component (A) in Examples 1 to 8,calcium-carbonate-perbasic calcium (monoalkyl)salicylates having a metalratio of 2.7 (about the constituent ratios of monoalkylsalicylates inthe salicylate structure thereof, the ratio of C9371 manufactured byInfineum Co. (corresponding to SAP 001 manufactured by previous ShellChemicals Japan) was 96% by mole and that of OSCA 463 manufactured byOsca Chemical Co. was 95% by mole) and calcium sulfonate having a metalratio of 1 (Comparative Examples 1, 2, 5 and 6), a white precipitationwhich appeared to be calcium carbonate was evidently generated withinone week. In the case of using calcium (monoalkyl) salicylate having ametal ratio of 2.7 together with perbasic calcium sulfonate having ametal ratio of 10 (Comparative Examples 3, 4, 7 and 8), the sameprecipitation was evidently generated within 2 weeks. Thus, it isunderstood that they were poor in storage stability.

INDUSTRIAL APPLICABILITY

The lubricating oil additive and the lubricating oil composition of thepresent invention generate no precipitation and have good storagestability. It has been become possible to supply a lubricating oiladditive product or a lubricating oil composition product made of acombination of a (per)basic salicylate and a metal detergent such as(neutral) sulfonate, which has generated a precipitation so as not to becirculated as a product so far or so as to cause a trouble even if ithas been circulated. It has been become possible to prevent thegeneration of troubles even under a situation that asalicylate-containing lubricating oil is mixed with anothermetal-detergent-containing lubricating oil or a situation that these aremixed with each other when the kind of oil is exchanged in a storagetank. It has been verified that the lubricating oil additive and thelubricating oil composition of the invention are good inhigh-temperature detergency and oxidation stability and can be made highin long drain property. It is also possible to give a desiredperformance to the additive or composition by incorporating variousadditives thereinto. Accordingly, the lubricating oil additive and thelubricating oil composition of the invention are useful as a lubricatingoil additive or a lubricating oil composition, and can be preferablyused as a lubricating oil additive and a lubricating oil composition forinternal combustion engines such as gasoline engines, diesel engines andgas engines for two-wheeled vehicles, four-wheeled vehicles, powergeneration, ships or the like, in particular, a lubricating oil additiveand a lubricating oil composition for internal combustion engines usinglow-sulfur fuels (for example, gasoline, light oil, natural gas and LPGwhich have a sulfur content of 50 ppm or less by mass, preferably 10 ppmor less by mass, or hydrogen, dimethyl ether (DME), gas-to-liquid (GTL)fuels (light oil fractions and gasoline fractions) and alcohol fuelwhich do not substantially contain sulfur) since long-drain performancecan be made higher.

Moreover, the lubricating oil additive and the lubricating oilcomposition of the invention can be preferably used as a lubricating oilabout which storage stability, high-temperature detergency and oxidationstability as described above are required, for example, a lubricatingoil for a driving system such as an automatic or manual transmission, ora lubricating oil such as grease, wet brake oil, hydraulic oil, turbineoil, compressor oil, shaft bearing oil or refrigerator oil, and as anadditive used therein.

1. A lubricating oil additive obtained by incorporating, into alubricant base oil, (A) a salicylate detergent and (B) a metal detergentother than any salicylate detergent, wherein the salicylate detergent(A) is an alkali metal or alkaline earth metal salicylate represented bythe general formula (1) and/or a (per)basic salt thereof:

wherein R¹ and R² may be the same or different and each represent ahydrocarbon group having 1 to 40 carbon atoms, the hydrocarbon group maycontain oxygen or nitrogen, m represents an alkali metal or alkalineearth metal, and n is 1 or 2 in accordance with the valence of themetal.
 2. The lubricating oil additive according to claim 1, wherein oneof R¹ and R² in the general formula (1) is a hydrocarbon which has 10 to40 carbon atoms, and the other is a hydrocarbon which has less than 10carbon atoms (and may have oxygen or nitrogen).
 3. The lubricating oiladditive according to claim 1, wherein R¹ and R² in the general formula(1) are each a hydrocarbon group having 10 to 40 carbon atoms.
 4. Thelubricating oil additive according to any one of claims 1 to 3, whereinthe component (A), has a metal ratio of 1.1 or more.
 5. The lubricatingoil additive according to any one of claims 1 to 4, wherein the metaldetergent (B) other than any salicylate detergent is at least oneselected from alkali metal or alkaline earth metal sulfonates and(per)basic salts thereof.
 6. The lubricating oil additive according toany one of claims 1 to 5, which further comprises at least one selectedfrom (C) an anti-wear agent, (D) an ashless dispersing agent, and (E) anantioxidant.
 7. A lubricating oil composition, into which thelubricating oil additive according to any one of claims 1 to 6 isincorporated.
 8. A method for improving the storage stability of alubricating oil composition comprising a salicylate detergent andanother metal detergent, wherein the lubricating oil additive accordingto any one of claims 1 to 6 is used.